1. Field of the Invention
The present invention relates to an active matrix-type liquid crystal display (LCD) apparatus, and more particularly, to a twisted nematic (TN)-mode LCD apparatus having pixels of different orientation of liquid crystal.
2. Description of the Related Art
An active matrix-type LCD apparatus is thin, so that it is often used in various display apparatuses. In this type of active matrix-type LCD apparatus, since individual pixel electrodes are independently driven, the display contrast is not reduced based upon the reduction of a duty ratio.
As an active matrix-type LCD apparatus, a TN-mode type LCD apparatus where the orientation of liquid crystal between pixel electrodes and a counter electrode is twisted in an OFF state.
In a first prior art TN mode LCD apparatus, the orientation of liquid crystal for one pixel is uniform. This will be explained later in detail.
In the first prior art TN-mode LCD apparatus, however, since the orientation of liquid crystal molecules is not symmetrical with respect to the center thereof, the visual angle dependency characteristics are remarkably reduced.
In a second prior art TN-mode LCD apparatus, each liquid crystral for one pixel is divided into two TN layers. That is, a rubbing direction of one TN layer is opposite to a rubbing direction of the other TN layer. As a result, since the orientation of liquid crystal molecules is symmetrical with respect to the center thereof, the visual angle dependency characteristics are improved. This will also be explained later in detail.
In the second prior art TN-mode LCD apparatus, however, a discontinuity of orientation of liquid crystal is generated between the two TN layers. As a result, if the LCD apparatus is a normally-white-mode apparatus, leakage of light through the discontinuity of orientation of liquid crystal reduces the display contrast.
In a third prior art TN-mode LCD apparatus (see JP-A-5-224210), a light shield layer is provided at the discontinuity of orientation of liquid crystal, which reduces the leakage of light therethrough. This will also be explained later in detail.
In the third prior art TN-mode LCD apparatus, however, the alignment of the light shield layer with the location of the discontinuity of orientation of liquid crystal is unstable, and therefore, it is difficult for the light shield layer to completely shield leakage of light through the discontinuity of orientation of liquid crystal.